In 1968, Dr. Kenneth Cooper published an article in Readers Digest on "aerobics," a method of physical exercise for producing beneficial changes in the respiratory and circulatory systems. One principle of aerobics requires that, to achieve optimum benefit, the subject maintain heart rate within a prescribed range for a prescribed duration. Training and exercising by heart rate has since become a generally accepted practice and, even though it is distracting and inconvenient, participants have learned to stop and take their pulse at intervals during exercise.
Recently, devices have been developed to aid the exerciser. The typical heart monitor is a device which provides a display, usually digital, of a subject's heart rate. A "runner's monitor" is available which senses distance travelled by means of ultrasonic echo, provides a voice output, and provides an input for a heart rate detector.
Heart rate monitors currently available include the following types:
1. Those which are portable. PA0 2. Those which are not portable and are often attached to particular exercise equipment. PA0 3. Those which measure heart rate when requested and require the subject to remain inactive while the reading is taken. PA0 4. Those which measure heart rate continuously while the subject is moving. PA0 5. Those which measure heart rate continuously and provide visual and/or audible alarm signals when the subject's heart rate goes above/below pre-determined limits. PA0 6. Those which include timing functions such as a stop watch.
Since they are display-oriented devices, previously available heart monitors share the drawback of being unable to notify the subject of other than alarm conditions without requiring constant attention to the display. Portable heart monitors have the further disadvantages of a relatively small display which is difficult for an actively exercising person to read (especially one who must wear glasses) and relatively small controls (switches, pushbuttons) which are inconvenient for the active exerciser to locate and actuate. Some also are cumbersome, requiring wires to be connected from one part of the body to another.
The runner's monitor is not appropriate as an aerobic fitness aid since it calculates average heart rate only on command and is, therefore, unable to monitor over/under heart rate conditions. It does not instruct the user of exercise sequence and is unwieldy in active exercise, requiring a belt-worn electronics package and separate, wire connected, heart rate detector and headphones.